The present invention relates to a method for removing the coating from a gas turbine component 1.
Components of a gas turbine, such as the blades, are provided with special wear protection coatings in order to provide resistance to oxidation, resistance to corrosion, or resistance to erosion on their surfaces. During operation of gas turbines, the components of these turbines are subjected to wear, or can be damaged in other ways. In order to repair damages, as a rule it is necessary to partly or completely remove or abrade the wear protection coating from the component to be repaired in some areas. The removal or abrading of coatings is also called de-coating or coating removal. A distinction is made between coating removal methods in which the coating removal takes place mechanically, chemically, or electrochemically.
Standardly, wear protection coatings are realized as what are known as multilayer coatings made up of a plurality of layers applied in alternating fashion to the gas turbine component. Thus, for example it is possible for a wear protection coating realized as a multilayer coating to comprise a relatively soft metallic layer and a relatively hard ceramic layer that are applied to the gas turbine component multiple times in alternating fashion one after the other. In addition, wear protection coatings are known from practical use in which more than two different layers are applied to the gas turbine component in alternating fashion one after the other, such as multilayer coatings made up of four layers that are applied to the gas turbine component in alternating fashion one after the other, namely a first, metallic and therefore relatively soft layer that is adapted to the material composition of the gas turbine component, another metallic layer that is also relatively soft and that is made of a metal alloy, a third, relatively hard graded metal-ceramic layer, and a fourth relatively hard ceramic layer.
Up to now, from the prior art no method has been known with which wear protection coatings fashioned as multilayer coatings can be effectively removed without running the risk of damaging the gas turbine component.